Hydrogen production of Enterobacter aerogenes altered by extracellular and intracellular redox states

Nakashimada, Yutaka; Rachman, Mahyudin Abdul; Kakizono, Toshihide; Nishio, Naomichi

doi:10.1016/s0360-3199(02)00128-3

Cited by 173 publications

(75 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This causal relationship between reductant concentration and hydrogen production has been proposed in heterotrophic bacteria (9), and Enterobacter aerogenes displays redox-linked hydrogen production with increased NAD(P)H/NAD(P) ϩ ratios driving increased hydrogen production (19). Further, the temporal link between NAD(P)H pool size and hydrogen production has been demonstrated previously in A. maxima (1).…”

Section: Discussionsupporting

confidence: 61%

Redirecting Reductant Flux into Hydrogen Production via Metabolic Engineering of Fermentative Carbon Metabolism in a Cyanobacterium

McNeely

Bennette

et al. 2010

Appl Environ Microbiol

143

View full text Add to dashboard Cite

Some aquatic microbial oxygenic photoautotrophs (AMOPs) make hydrogen (H 2 ), a carbon-neutral, renewable product derived from water, in low yields during autofermentation (anaerobic metabolism) of intracellular carbohydrates previously stored during aerobic photosynthesis. We have constructed a mutant (the ldhA mutant) of the cyanobacterium Synechococcus sp. strain PCC 7002 lacking the enzyme for the NADH-dependent reduction of pyruvate to D-lactate, the major fermentative reductant sink in this AMOP. Both nuclear magnetic resonance (NMR) spectroscopy and liquid chromatography-mass spectrometry (LC-MS) metabolomic methods have shown that autofermentation by the ldhA mutant resulted in no D-lactate production and higher concentrations of excreted acetate, alanine, succinate, and hydrogen (up to 5-fold) compared to that by the wild type. The measured intracellular NAD(P)(H) concentrations demonstrated that the NAD(P)H/NAD(P)؉ ratio increased appreciably during autofermentation in the ldhA strain; we propose this to be the principal source of the observed increase in H 2 production via an NADH-dependent, bidirectional [NiFe] hydrogenase. Despite the elevated NAD(P)H/NAD(P)؉ ratio, no decrease was found in the rate of anaerobic conversion of stored carbohydrates. The measured energy conversion efficiency (ECE) from biomass (as glucose equivalents) converted to hydrogen in the ldhA mutant is 12%. Together with the unimpaired photoautotrophic growth of the ldhA mutant, these attributes reveal that metabolic engineering is an effective strategy to enhance H 2 production in AMOPs without compromising viability.

show abstract

Section: Discussionsupporting

confidence: 61%

Redirecting Reductant Flux into Hydrogen Production via Metabolic Engineering of Fermentative Carbon Metabolism in a Cyanobacterium

McNeely

Bennette

et al. 2010

Appl Environ Microbiol

143

View full text Add to dashboard Cite

show abstract

“…The second phase of H 2 production in A. maxima is fueled by NADH generated from glycolysis and occurs only after an accumulation of excess NADH:NAD ϩ sufficient for the thermodynamic production of H 2 (1). The level of intracellular reductant pools correlates with H 2 production in certain strains of bacteria, including cyanobacteria (7,25,30). NADH has been shown to be the preferred exogenous electron donor for the cyanobacterial NiFe hydrogenase (44).…”

Section: Discussionmentioning

confidence: 99%

Synechococcus sp. Strain PCC 7002 nifJ Mutant Lacking Pyruvate:Ferredoxin Oxidoreductase

McNeely

Ananyev

et al. 2011

Appl Environ Microbiol

View full text Add to dashboard Cite

The nifJ gene codes for pyruvate:ferredoxin oxidoreductase (PFOR), which reduces ferredoxin during fermentative catabolism of pyruvate to acetyl-coenzyme A (acetyl-CoA). A nifJ knockout mutant was constructed that lacks one of two pathways for the oxidation of pyruvate in the cyanobacterium Synechococcus sp. strain PCC 7002. Remarkably, the photoautotrophic growth rate of this mutant increased by 20% relative to the wild-type (WT) rate under conditions of light-dark cycling. This result is attributed to an increase in the quantum yield of photosystem II (PSII) charge separation as measured by photosynthetic electron turnover efficiency determined using fast-repetition-rate fluorometry (F v /F m ). During autofermentation, the excretion of acetate and lactate products by nifJ mutant cells decreased 2-fold and 1.2-fold, respectively. Although nifJ cells displayed higher in vitro hydrogenase activity than WT cells, H 2 production in vivo was 1.3-fold lower than the WT level. Inhibition of acetate-CoA ligase and pyruvate dehydrogenase complex by glycerol eliminated acetate production, with a resulting loss of reductant and a 3-fold decrease in H 2 production by nifJ cells compared to WT cells. Continuous electrochemical detection of dissolved H 2 revealed two temporally resolved phases of H 2 production during autofermentation, a minor first phase and a major second phase. The first phase was attributed to reduction of ferredoxin, because its level decreased 2-fold in nifJ cells. The second phase was attributed to glycolytic NADH production and decreased 20% in nifJ cells. Measurement of the intracellular NADH/NAD ؉ ratio revealed that the reductant generated by PFOR contributing to the first phase of H 2 production was not in equilibrium with bulk NADH/NAD ؉ and that the second phase corresponded to the equilibrium NADH-mediated process.

show abstract

“…Spontaneous production of H 2 from formate and glucose by immobilized Escherichia coli showed 100% and 60% efficiencies, respectively. Enterobactericiae produce H 2 at similar efficiency range from different monosaccharides (Fabiano & Perego, 2002;Nakashimada et al, 2002;Tanisho & Ishiwata, 1995;Yokoi, et al, 1997Yokoi, et al, , 1998Yokoi, et al, , 2001). Among methylotrophs, methanogenes, rumen bacteria and thermophilic archae, Ruminococcus albus, are promising.…”

Section: Implication Of Phototrophs In Environmental Clean Up and Upgmentioning

confidence: 99%

“…Besides the availability of rich diversity of other microbes for such fermentative processes phototrophic, purple non-sulfur bacteria, have to been exploited for example they have been explored to treat odorous swine based water (Kim et al, 2004;Nath & Das, 2004). Likewise purple non-sulfur bacteria have been described for treatment of domestic and industrial effluents of varying chemical nature (Lay, 2001;Najafpour et al, 2006;Nakashimada et al, 2002;Nath & Shukla, 1997;Zhu et al, 1995).…”

Section: Treatment Of Wastewater By Purple Non-sulfur Bacteriamentioning

confidence: 99%

Biofuel From Cellulosic Mass with Incentive for Feed Industry Employing Thermophilic Microbes

Qazi¹,

Chaudhary²,

Mirza³

2011

Biofuel Production-Recent Developments and Prospects

View full text Add to dashboard Cite

Hydrogen production of Enterobacter aerogenes altered by extracellular and intracellular redox states

Cited by 173 publications

References 24 publications

Redirecting Reductant Flux into Hydrogen Production via Metabolic Engineering of Fermentative Carbon Metabolism in a Cyanobacterium

Redirecting Reductant Flux into Hydrogen Production via Metabolic Engineering of Fermentative Carbon Metabolism in a Cyanobacterium

Synechococcus sp. Strain PCC 7002 nifJ Mutant Lacking Pyruvate:Ferredoxin Oxidoreductase

Biofuel From Cellulosic Mass with Incentive for Feed Industry Employing Thermophilic Microbes

Contact Info

Product

Resources

About